Reduced Glutathione (γ-glutamylcysteinylglycine; GSH) is a tripeptide consists of glycine, cysteine and glutamate. It exists naturally in the cytosol of most cells in the human body and functions as a key mediator in several enzymatic processes that are crucial to detoxification of harmful heavy metals and for continuous quenching of free radicals. In the meantime, GSH also plays a significant role in supporting many human metabolic processes that are closely related to one's overall health (e.g. amino acid transportation, deoxyribonucleic acid synthesis and immune system augmentation). In the respiratory tract, GSH is widely considered the first line of defence against oxidative stress.

However, GSH levels in the human body can be severely depleted as a result of smoking, exposure to air pollution and other toxins, medication, stress and poor dietary habits. Scientific studies have linked low levels of GSH in the human body to respiratory diseases, cancer, cardiovascular disease, neurological diseases such as Alzheimer’s and Parkinson's, and aging in general.

On the other hand, scientific studies have proven that GSH supplementation can help with a range of lung conditions (Prousky, 2008). Intra-oral spray administration of GSH is the most effective method for restoring GSH levels in lung (Wendel and Cikryt, 1980; Buhl et al, 1990).